The present invention is directed to bicycles and, more particularly, to a bicycle hub that uses a braking mechanism.
A typical bicycle hub generally includes a hub shaft that is detachably and non-rotatably mounted to the fork (frame) of the bicycle, a cylindrical hub shell (outer shell) that is mounted around the hub shaft, and bearings that rotatably support the hub shell to the hub shaft. Hub flanges are formed at opposite ends of the hub shell for mounting the hub shell to the spokes of the wheel. A brake apparatus that controls the rotation of the hub shell relative to the hub shaft may be mounted between the bicycle frame and the hub shell. In some bicycles, a braking force control mechanism that includes a friction clutch may be mounted inside the hub. The braking force control mechanism provides an antilock function for the hub by causing the friction clutch to slip when the brake apparatus applies a potentially excessive braking force.
A conventional braking force control mechanism has a brake-side member that engages a portion of the brake apparatus (e.g., a brake drum), a friction engagement unit that creates a friction force in a brake force path between the hub shell with the brake-side member, and a friction force adjustment unit that adjusts the friction force of the friction engagement unit. The friction engagement unit comprises a plurality of first friction members and a plurality of second friction members, wherein the plurality of first friction members nonrotatably engage the brake-side member, the plurality of second friction members nonrotatably engage the hub shell, and the plurality of first friction member are interleaved with the plurality of second friction members. The plurality of first friction members and the plurality of second friction members are sandwiched between the brake side member and the friction force adjustment unit. More specifically, the friction force adjustment unit includes a nut member and a spring washer, wherein the nut member screws to the brake side member and the spring washer is disposed between the nut member and the plurality of first and second friction members. Screwing the nut member toward the brake side member causes the spring washer to press against the plurality of first and second friction members, thus increasing the friction force between the first and second friction members. Conversely, screwing the nut member away from the brake side member causes the spring washer to move away from the plurality of first and second friction members, thus decreasing the friction force between the first and second friction members.
The braking force control mechanism usually is housed inside the hub shell. Accordingly, such braking force control mechanisms usually are adjusted prior to assembly within the hub shell. When adjustment of the braking force control mechanism is completed, the hub shell, bearings and hub shaft are assembled, thereby completing assembly of the hub. However, during assembly of the hub there is a possibility that the plurality of first or second friction members may be slightly deformed or otherwise altered in position such that the set friction force changes. If that happens, the hub must be disassembled so that the braking force control mechanism may be readjusted, and then the hub must be reassembled. Therefore, if the friction force changes, time-consuming and labor-intensive work must be carried out in order to readjust the braking force.